Bulk materials are typically characterized using electrical resistivity measurements as a function of pressure doping, temperature, and applied field. However, as the dimensionality of the sample reduces, the magnetic field’s orientation to the sample becomes more crucial.

The alignment of the field to the sample in extremely anisotropic materials enables the analysis of exotic phases of matter including electron gases in topological insulators and semiconductors.

As the dimensions further reduce, magnetic fields can be used to manipulate electron transport, exposing new physics such as quantized transport and Majorana fermions.

The Challenges

Without any access to the sample, how could one alter the orientation of the field to the sample?

How can electrical contact be maintained with the sample?

How could a large magnetic field be rotated relative to the sample?

How can the Fermi surface of a sample be probed?

How can corrections be done for any misalignment of a sample to the magnetic field?

Oxford Instruments has the Solution

Mechanical Rotator

For measurements necessitating high magnetic fields, a mechanical motor can be employed to rotate the sample within the magnetic field. With a rotating sample, flexible electrical connections are possible.

Incorporating the mechanical drive rod with a stepper motor at room temperature, allows the sample angle to be fixed accurately

Permits access to larger magnetic fields than a vector magnet

Piezoelectic Rotator

For measurements where a high magnetic field is necessary, but where it is not possible to fit a drive rod, a piezoelectric rotator can be employed. In this configuration, the rotator is driven electrically and an encoder can be used to establish the sample’s angle.

Electrically driven

Allows access to larger magnetic fields than a vector magnet

Can be set up on systems where a mechanical drive rod will not be suitable

Simplified design without the need for a mechanical linkage between sample and room temperature

When integrated with a mechanical rotator, it allows rotation in numerous axes

Vector Magnet

A vector magnet, containing two or more orthogonal superconducting coils, allows the field orientation to be regulated by varying the current in each coil. This enables the field to be swept through complex paths in numerous axes.

Measurements necessitating higher frequency lines or optical access to the sample are feasible as the sample is fixed.

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